place 2 repeating command blocks

First: /replaceitem entity @p slot.armor.chest minecraft:leather_chestplate 1 0 {HideFlags:7,Unbreakable:1,AttributeModifiers:[

{AttributeName:"generic.maxHealth",Name:"generic.maxHealth",Operation:0,UUIDMost:77362,UUIDLeast:922264,Amount:-14}

]}

Second: /effect @p minecraft:poison 3 5

and than kill yourself

one is dead although it is not dead ?!?! you can press F5